1. Field of the Invention
The present invention relates to an apparatus and method for measuring concentrations of components which are suitable for use in carrying out non-destructive measurements and/or non-invasive, bloodless measurements.
2. Description of the Prior Art
Conventionally, in the fields of biology and medicine, a near infrared CT (computed tomography) has been known which enables a non-invasive, bloodless examination of an object. This technique utilizes the so-called time of flight method for near infrared rays in scattering optical system. For example, in the case of the near infrared CT, a pulse laser is irradiated toward the object from one side thereof for time-resolved measurement of quantity of light passing through the object which change with lapse of time, data for the changing quantity of light being disregarded except the data for the quantity of light which has passed through the object for an initial very short time period. An image of the interior of the object is formed on the basis of the data for the quantity of light obtained during the initial short time. In other words, the light which has reached the photoreceptor in the initial short time are considered as having passed through the interior of the object along the shortest possible optical path and only data for that quantity of light is used to obtain a clear and sharp image.
In the conventional near infrared CT, only an initial portion of the transmitted light varying with time lapse is utilized to obtain information on the interior of the object. For the purpose of measuring a concentration of a component in the object, however, it is not necessarily suitable to adopt the same concept as that of the near infrared CT.
In order to accurately determine a concentration of a component, it is necessary to increase the measurement accuracy of a measuring system, and for this purpose it is necessary to enhance the S/N ratio of the measuring system.